This invention relates to a base station for use in a radio communication network. This invention relates also to a radio communication network which includes the base station.
A radio communication network of the type described, comprises a base or fixed station, at least two telephone lines, and a plurality of radio telephone sets which are not less in number than the telephone lines. The telephone lines may be subscriber lines extended from a central exchange of a central station. Alternatively, the telephone lines may be extension lines which are extended from a private branch exchange. Each radio telephone set may be a mobile telephone set, a cordless telephone set, or the like.
A conventional base station comprises radio transceivers which are not less in number than the above-mentioned radio telephone lines. A station controlling device is coupled to the telephone lines for controlling the radio transceivers to connect the telephone lines to the radio telephone sets through a control channel and a plurality of communication channels which are not less in number than the telephone lines and are given channel codes, respectively. The communication channels are speech channels or data channels.
Responsive to a first arrival signal arriving at one of the telephone lines, the station controlling device selects one of idle transceiver and one of transceivers as a first selected transceiver and one of idle channels among the communication channels as a first selected channel. Subsequently, the station controlling device makes the first selected transceiver send the first arrival signal and the channel code of the first selected channel through the control channel towards the radio telephone sets.
Thereafter, the station controlling device produces a first call signal and makes the first selected transceiver send the first wall signal through the first selected channel towards the radio telephone sets. More specifically, such a call signal is a tone generator driving signal, namely, a well driving signal.
Each of the radio telephone sets comprises a tone generator, namely, a bell, responsive to the tone generator driving signal for generating a call tone. Thus, the radio telephone sets generate call tones, respectively, in response to the first call signal received through the first selected channel after reception of the first arrival signal and the channel code of the first selected channel through the control channel. One of the radio telephone sets, which generate the respective call tones, transmits a response or off-hook signal through the first selected channel to the first selected transceiver when the above-mentioned one of the radio telephone sets comes to an off-hook state.
Responsive to the response signal, the base station stops sending the first call signal through the first selected channel towards the radio telephone sets. Thereafter, the base station connects the above-mentioned one of the telephone lines to the above-mentioned one of the radio telephone sets through the first selected channel so that the above-mentioned one of the radio telephone sets can communicate a communication signal, such as a speech signal or a data signal, with the above-mentioned one of the telephone lines through the first selected channel.
It will be assumed that the base station receives a second arrival signal arriving at a different one of the telephone lines while the first call signal is sent through the first selected channel towards the radio telephone sets. In this case, the base station receives the second arrival signal before the base station stops, in response to the response signal, sending the first call signal. When the base station receives the second arrival signal, the base station waits for reception of the response signal. When the response signal is received, the base station connects the above-mentioned one of the radio telephone sets to the above-mentioned one of the radio telephone sets through the first selected channel and, thereafter, selects another one of the idle channels as a second selected channel to send the second arrival signal and the channel code of the second selected channel through the control channel. The base station is, therefore, incapable of rapidly responding to an arrival signal received from a telephone line immediately after reception of a preceding arrived signal from another telephone line.
Thus, the conventional base station uses the control channel to send an arrival signal whenever the arrival signal is received . Such an arrival signal is sent regardless of whether or not the base station sends the call signal through the first selected channel towards the radio telephone sets at that time. As a result, he control channel is frequently used and traffic of the control channel is increased.